The present invention relates to a disc brake, in particular for a utility vehicle, having a brake caliper which surrounds a brake disc and is attached to a brake carrier of the utility vehicle so as to be axially displaceable with respect to the brake disc. Two attachment elements are typically used with one attachment element being embodied as a fixed bearing and the other being embodied as a loose bearing having a sliding bush inserted into a bore in the brake caliper. The internal contour and/or external contour of the bushing deviates from a circular shape and a guide bar which is, for example, round in cross section is guided in the sliding bush.
Accordingly, in such disc brakes, the brake caliper is connected by attachment elements to the brake carrier, which is fastened to the vehicle. At the same time, guide bars engage in the brake carrier and are, on the other hand, guided in sliding bearings of the brake caliper such that an axial displacement of the brake caliper with respect to the fixed brake carrier is possible. One of the sliding bearings is embodied as a fixed bearing with little sliding play, while the other functions as a loose bearing, as a result of which, in particular, fabrication tolerances are compensated.
In order to bring about such compensation it is known to provide the sliding bushing with a bore with, in the broadest sense, an oval cross section, in which case the greatest width of this bore extends transversely with respect to the axial direction so that the guide bar can migrate laterally in both directions with respect to the longitudinal center axis. As in the case of the fixed bearing, overall there is also no play or only a very small amount of play provided perpendicularly thereto.
However, for the sliding bushing to be fully operationally capable it is necessary for it to be positioned in a permanent and precise fashion, which includes both securing against axial displacement and securing against rotation.
In series fabrication of disc brakes, such precisely positioned securing is achieved, for example, by virtue of the fact that the sliding bushing is caulked to the brake caliper. It is also known to secure the sliding bushing in the brake caliper by using a form fit. Suitable tools which permit correspondingly precisely positioned insertion without difficulty are available for this for series fabrication.
In contrast, such precisely positioned mounting of the sliding bushing is not ensured when replacement is carried out for the purpose of repair so that, hitherto, incorrect positioning of the sliding bushing has readily occurred, which may lead to functional problems.
In all cases, the insertion of the sliding bushing into a predetermined position and its securing in this position have been able to be implemented only with considerable effort.
The invention is, therefore, based on developing a disc brake of the above-mentioned type in such a way that the sliding bushing may be introduced and secured permanently in any of its possible directions of movement using structurally simple mechanisms.
This is achieved by providing a disc brake, particularly for a commercial vehicle, having a brake caliper which surrounds a brake disc and is attached to a brake carrier of the utility vehicle so as to be axially displaceable with respect to the brake disc. Two attachment elements are typically used with one attachment element being embodied as a fixed bearing and the other being embodied as a loose bearing having a sliding bush inserted into a bore in the brake caliper. The internal contour and/or external contour of the bushing deviates from a circular shape and a guide bar which is, for example, round in cross section is guided in the sliding bush. The sliding bushing of the loose bearing is provided with at least one securing element which, when the sliding bushing is mounted in a precisely positioned fashion, is inserted into a recess of the bore such that it secures said sliding bush.
The inventive embodiment of the sliding bushing of the loose bearing of a disc brake ensures that, when it is completely assembled, the sliding bushing reliably assumes the correct predetermined position so that the functional capability of the loose bearing is ensured without limitation.
In this context, the securing element may be composed of at least one securing clip, which projects over the outer surface of the sliding bushing in the position of use of the loose bearing and is inserted into a recess of the bore in the brake caliper.
Before it corresponds to the recess of the bore, which may be embodied as a pocket, the securing clip projects into the inner bore of the sliding bushing and, as a result, closes off a free passage of the guide bar. When the guide bar is installed, the securing clip must therefore project into the recess of the bore in order to provide a free passage for the guide bar. In this way, virtually a double securement is provided for ensuring that when the sliding bushing is completely assembled it both assumes the predetermined position and remains secured in this position.
Especially for maintenance or repair work, this provision is particularly significant since incorrect installations are virtually ruled out.
In principle there may be any desired number of securing elements, i.e. of securing clips. The number of securing elements may be selected in accordance with the requirements for the necessary securing force.
Simple mounting is ensured by the lowest possible number of securing clips, preferably just one securing clip, while a plurality of securing clips is provided when there are large axial and/or rotational forces.
The shape of the securing clips may, in principle, also be selected freely. However, they must be shaped in such a way that they reliably prevent the guide bar from being pushed through, i.e. measure mounting, if the securing clips are not inserted into the recesses of the bore.
The securing clips and the recesses which are assigned to them, preferably in the form of pockets, are matched to one another in terms of shape and dimensions such that when they correspond to one another a large degree of positive locking is produced, which ensures that the sliding bushing is secured both circumferentially and axially.
Overall, this results not only in an advantage in terms of safety, but also a considerable advantage in terms of mounting since the installation of the sliding bushing may now be carried out significantly more easily and quickly. This is particularly the case when the sliding bushing is changed for maintenance reasons, for which the tools which are available during series mounting are neither available nor usable.
According to a further aspect of the invention, there is provision for the securing clips to be formed from the sliding bushing in an integral fashion. In such a case, as mentioned, the securing clips first project into the space formed by the inner bore and are then bent into the recess of the bore until they bear against the wall of the recess in such a way that the sliding bushing is prevented from moving in any direction. In this position, the guide bar, which is to be inserted, can be passed freely through the inner bore.
Further advantageous embodiments of the invention are described and claimed herein.